Smoke generator and toy smoke-ring gun using same

ABSTRACT

A toy gun ( 10 ) produces a series of traveling smoke rings ( 12 ). It has a smoke chamber ( 14 ) fed with smoke from a battery ( 24 )-powered electrical resistance generator ( 30 ). An elastic, edge-mounted diaphragm ( 74 ) extends across at least a portion of the rear of the smoke chamber ( 14 ). A reciprocating actuator ( 68 ) movable in response to a trigger ( 22 ) strikes the diaphragm ( 74 ) to eject a smoke ring ( 12 ) through an orifice ( 14   d ) in the opposite wall ( 14   a ) of the smoke chamber ( 14 ). The smoke generator ( 30 ) includes a supply tank ( 32 ) of a suitable liquid ( 34 ) and a source ( 36 ) of variable pressure to drive the liquid ( 34 ) through a narrow annular clearance ( 43 ) to the heater ( 38 ) where it is rapidly vaporized. The generator ( 30 ) includes a pair of concentric tubes ( 40,42 ) that define the annular clearance ( 43 ) and an electrical resistance heating element ( 38 ) mounted on one of them at a point spaced from the supply tank.

FIELD OF THE INVENTION

[0001] The invention generally relates to apparatus for producing smoke,steam or fog, and more particularly, to a toy gun that produces one ormore traveling smoke rings when fired.

BACKGROUND

[0002] Various toys are known that utilize smoke, steam, and fog(herein, collectively, “smoke”) generators, and a variety of generatorsfor producing smoke for toys, theatrical productions, and the like arealso known. See, e.g., U.S. Pat. No. 3,891,826. Liquid mixturesspecifically designed for use in such generators are also known. See,e.g., U.S. Pat. No. 3,342,746.

[0003] Toy guns have captured the popular imagination for many years.Metcalf, E. W. and Maresca, F., Ray Gun (1999) Fotofolio, Inc., NewYork, N.Y. is devoted to one type of toy gun, a ray gun. In particular,smoke-producing toy guns are known. U.S. Pat. No. 2,855,714 describes atoy gun that produces smoke rings through the detonation of percussivecaps within the gun casing.

[0004] While the visual effects and realism of smoke-producing toy gunsare significant advantages, a number of drawbacks have limited theircommercialization. For example, many prior smoke generators for toysemploy mixtures that are not always completely safe. In particular, manyoils and oil-based mixtures for making smoke have not been approved forhuman use. Children may be especially prone to injury from exposure toor mishandling of such fluids, or to heaters used to vaporize liquids tomake smoke.

[0005] Many prior generators, such as those employed in model railroads,have an open smoke producing device, usually a chimney on an engine,that operates continuously. This arrangement is not conducive toproducing smoke rings. It also can be sensitive to orientation—a smokegenerator for a fixed, upright smokestack on a model train may notfunction, or function well, when used in a toy that may assumeorientation other than upright. Further, continuous smoke production andthe power requirements of such production also militate against theportability of the toy or other device using smoke.

[0006] Prior toy guns have used detonation of percussion caps to makesmoke. This arrangement is portable and does not require electricalpower, but it clearly may not be suitable for use by or near childrenbecause of the harmful percussion cap explosions. Percussion caps alsoproduce the noise of a cap explosion, which may be a negative attributeto many.

[0007] U.S. Pat. No. 3,342,746 to Seuthe discloses oil-based fluids anda generator for producing smoke. As noted above, such fluids may not becompletely without adverse health reactions, particularly when used inclosed rooms. In particular, exposure to such fluids in aerosol form canproduce significant eye, nose and throat discomfort.

[0008] A later Seuthe patent, U.S. Pat. No. 3,891,826, describes a smokegenerator that relies on a capillary action to draw the liquid from acentral, open-top reservior to a heated region where it vaporizes toprovide a smoke or fog. Such generators require an upright orientationfor optimal use (due to the effect of gravity on a capillary action thatfeeds fluid to a resistance heater) and to avoid fluid loss, e.g., dueto an outflow from the fluid reservoir. Also, use of electricalresistance wires or coiled wires in many prior generators to vaporize afluid has presented unacceptable power requirements for portable devicesoperated with batteries. With model railroads, in contrast, power istypically supplied by household electrical current through a step-downtransformer. Further, the narrow clearances and related manufacturingrequirements make the Seuthe generator comparatively difficult tomanufacture.

[0009] It is therefore a principal object of this invention to provide asmoke generator that is portable, safe, fast-acting for non-continuousoperation, has comparatively low power requirements, and issubstantially orientation insensitive.

[0010] Another principal object of this invention is to provide aportable, battery-powered smoke-ring gun that uses electrical resistanceheating to produce the smoke.

[0011] A further object is to provide a smoke ring gun with theforegoing advantages of the smoke generator of the present inventionthat also has a favorable cost of manufacture.

[0012] A still further object is to provide a smoke ring gun with theforegoing advantages that can generate smoke from a water-based liquid.

SUMMARY OF THE INVENTION

[0013] The present invention provides apparatus for producing smoke anda toy gun that fires to produce smoke in a traveling ring shape, and inparticular is capable of producing a succession of smoke rings travelingfrom the gun in its direction of aim. A particular toy gun includes asmoke chamber fed by an electrical resistance smoke producing generator.The chamber has an elastic, edge-mounted diaphragm, or equivalentmoveable member, that co-acts with the chamber and an outlet orificeformed in a front wall of the chamber to produce the smoke rings. Thesmoke generator used in the gun is preferably the smoke generator of thepresent invention. The generator and toy gun can operate withwater-based smoke-producing liquids.

[0014] The invention includes a smoke generator that includes at leastone, and preferably all, of the following components:

[0015] a) a supply tank that holds the liquid,

[0016] b) a source of variable fluid pressure (e.g. air) in sealed fluidcommunciation with the supply tank for increasing and decreasing fluidpressure in the tank to feed the liquid to and from a heating unit; and

[0017] c) a heater adapted to receive and vaporize a small portion ofthe liquid fed from the suppply tank in response to an increase in thefluid pressure.

[0018] In a preferred form of the invention, the heating unit includesat least one and preferably all of the following components:

[0019] d) a first tube with a first end entering into the supply tank,and a second smoke outlet end; and

[0020] e) a heater positioned at least partially within the first tubefor vaporizing the pressurized liquid driven by an increase in thepressure into a narrow annular region between the heating element andthe surrounding tube.

[0021] The spacing is such that the pressure increase feeds the fluid toa region adjacent the heater on rapid vaporization, but does not usuallyoverflow the tube, or have a sufficient thermal mass that rapidvaporization of the liquid is difficult. Typically, the heater is anelectrical resistance wire that is coiled. When used in a toy gun of thepresent invention, the variable fluid pressure source is preferably abulb made from a pliable material, such as rubber, or the like.

[0022] The resistance coil is preferably sealed within a heat conductivetube, e.g., a glass tube. In most invention embodiments, the heatingelement will be suspended in the first tube, usually by means of one ormore lead wires to the electrical resistance wire. Also in the preferredform, a second metal tube concentrically surrounds the first tube formechanical protection and insulation. Overflow and condensate that flowto the bottom of the generator are drained to a closed collectioncompartment.

[0023] In a preferred embodiment, the smoke generator is positionedbelow and in fluid communication with the first chamber. Also, the smokegenerator is actuated by 1) an electrical on-off switch that controlsthe flow of current from a battery or batteries, preferably secured in ahandle or grip portion of the gun body, to the electrical resistancewire, and 2) a variable pressure liquid supplier, e.g. a flexible rubberbulb that is squeezed by the user to create a positive air pressure in aliquid supply tank, thereby forcing smoke liquid to the heater.Typically, this produces an instant burst of smoke filling the smokechamber. When the pressurized fluid supplier is disengaged (released),negative pressure is delivered to the tank, which in turn clears all, ormost, of the smoke liquid from the generator.

[0024] The invention also provides a toy gun that includes at least oneand preferably all of the following components:

[0025] a) gun body,

[0026] b) a smoke chamber at one end of the gun body and having spacedapart front and rear walls and a side wall,

[0027] c) a member movable axially to form pressure waves within thesmoke chamber forming at least a portion of said rear wall,

[0028] d) an orifice in said front wall,

[0029] e) a smoke generator operably coupled to the smoke chamber thatincludes a system for pressurizing a liquid and heating same to vaporizethe liquid to produce smoke; and

[0030] f) an actuator, preferably an elongated member mounted in the gunbody for an axial sliding movement and spring-driven toward a forwardposition where it strikes the diaphragm to create a pressure wave insidethe smoke chamber that interacts with the orifice to produce a travelingsmoke ring.

[0031] The smoke generator is preferably the smoke generator of thepresent invention. It is battery-powered and has an electricalresistance heater that vaporizes a portion of a liquid from a supply ofthe liquid carried in the gun. The movable member is preferably a latexrubber sheet of generally circular configuration, but is edge-mounted,preferably with a low tension across the sheet. The actuator head ispreferably rigid. The drive-spring is preferably adjustable to vary thestrike force of the actuator on the diaphragm. The actuator isoperatively coupled to a trigger that cocks, and then releases, theactuator to move under the forces of the compressed spring. The smokegenerator preferably uses a flexible bulb, activated by a second triggeras a hand grip, to produce smoke for the smoke chamber. A light sourceis provided in the smoke chamber. It can be actuated by the same switchthat powers the smoke generator, although in other embodiments the lightsource may be controlled by a separate switch.

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Still other features, advantages and aspects of the presentinvention will become more apparent from a description of illustrativeembodiments hereinafter, when read in conjunction with the drawings ofwhich:

[0033]FIG. 1 is a view in side elevation, showing a toy smoke-ring gunaccording to the present invention, and a succession of traveling smokerings produced by the gun;.

[0034]FIG. 2 is a view in vertical cross-section of a preferredembodiment of a smoke-ring gun according to the present invention;

[0035]FIG. 3 is an enlarged view in vertical cross-section of the smokegenerator shown in FIG. 2; and

[0036]FIG. 4 is a detailed view in vertical section corresponding toFIG. 3 showing an alternative form of a smoke-generator according to thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] FIGS. 1-3 show a toy smoke-ring gun 10 according to the presentinvention and a succession of smoke rings 12 produced by the gun 10. Therings 12 are ejected from a smoke collection chamber 14 located at thefront of the gun 10 and secured, e.g. by a set of struts 11, on a gunbody 16. The rings travel axially in the direction of arrow 18. In thepreferred form shown, the gun 10 is in the form of a pistol with a handgrip 20 and a trigger 22. As will be described below, the form, numberand speed of the smoke rings are all adjustable. Smoke is produced by auser of the gun on demand to fill the chamber 14. Rings can be generatedautomatically, but preferably one ring is produced with each pull of thetrigger 22 provided that there is sufficient smoke accumulated in thechamber 14. The gun 10 is preferably powered by batteries 24. Theoperation of the gun 10 is invariant to its orientation. It can beplaced on its side when not in use without spilling a liquid supply heldin a tank 32 and vaporized in small volumes to create the smoke.However, when not in use, in its presently preferred form shown in FIGS.2 and 3, the gun 10 rests on a flat-bottomed base 28 found at the bottomof the hand grip 20 and serving as a holding compartment for multiplebatteries 24. The weight of the batteries, and the configuration of thebase, provide a stable support for the gun 10 when it is not in use.

[0038] A central feature of the present invention is an on-demand,battery-powered, orientation-insenstiive, smoke generator 30 shown indetail in FIG. 3, and in an alternative form, in FIG. 4 (like partsbeing marked with the same reference number in both figures). Thesmoke-ring generator 30 includes the tank 32 that holds a supply of aliquid 34 to be vaporized, an air-filled rubber bulb 36 to pump theliquid to a heating region, and a heater 38, preferably one using anelectical resistance heating wire. The wire is preferably coiled, andwill be referred to herein as a “coil”, but the term “coil” is notlimited to a resistance heater element that is actually in a helical orcoiled form. As shown, the generator is in its preferred orientation,with arrow 31 indicating the vertical.

[0039] A tube 40 is mounted generally vertically through the upper wallof the tank 32 so that the bottom of the tube 40 ends slightly above thebottom of the tank. A high temperature glass tube 42 of the heater 38 ismounted coaxilly inside the metal tube 40, with a narrow annular space43 therebetween. The bottom of the glass tube is above the top of theliquid 34 in the tank 32. The top of the glass tube 42 extends above thetop of the metal tube 40. Inside the glass tube 42 an electricalresistance wire or coil 44 is positioned so that the top of the coil isjust below the top of the metal tube 40, and the bottom of the coil iswell above where the metal tube 40 goes through the tank 32. Theposition of the coil limits heat transmission principally to the area ofconnection between the metal tube 40 and the tank housing 32. The glasstube 42 extends above the metal tube 40 so that an electrical lead 46cannot touch the metal tube 40. Both ends of the glass tube 42 are fusedso that the tube and leads are sealed and impervious to moisture. Air ispreferably not evacuated from the glass tube 42 for better heatconduction to the outer surface, but operation with some degree of avacuum in the tube is possible. A bottom lead 48 extends through theglass tube 42 and out the end of the metal tube 40 so that it can beeasily connected to the bottom outside of the metal tube 40. A durableelectrical connection 47 is connected to the outside of the metal tube40 and extended outside the tank 32.

[0040] A larger metal tube 50, preferably formed of brass, is mountedcoaxially outside of the metal tube 40 so that the top of the metal tube50 extends above the top of the glass tube 42, and the bottom of thismetal tube 50 extends just above the bottom of the glass tube 42. Thisouter metal tube 50 acts as an insulator, protects the inner, relativelydelicate, tubes 40,42 from damage, and protects against human contactwith any components at the high heat of the coil 44. Also, the tube 50becomes an electrical conductor so that the lead 46 from the top of thecoil 44 so that a durable electrical lead 52 can be connected to thetube 50.

[0041] The liquid 34 is loaded through the tank filler hole 34 a. Arubber stopper 54 seals the tank 32 so that no air or fluid can escape.The rubber bulb 36 is mounted on an air delivery tube 56 that extends toan air-tight connection 58 to the tank 32. Because the only vent toatmosphere from the heater is the tube 40, the liquid 34 does not flowout of the heater when the gun 10 is laid on its side, or even when itis held upside down, just as olive oil will not pour easily from a canthat has only one small hole punched in its upper end. Thischaracteristic of the smoke generator is referred to herein as “closed”.

[0042] Although the close fit between the glass tube 42 and the metaltube 40 could be considered a capillary space, the opposite effect isdesired. When the rubber bulb 36 is squeezed, air is delivered to thetank 32 which in turn exerts positive fluid pressure on the liquid 34.This liquid is pumped up into the metal tube 40 and over the glass tube42 where it is vaporized rapidly by the high heat produced by the coil44. When the rubber bulb 36 is released, negative pressure is deliveredto the tank 32. This allows the coil 44 to rapidly heat to its highesttemperature without loss of heat to the liquid. Also, the evacuation ofthe fluid from the region around the coil 44 in response to a decreasefrom the increased (pumping) fluid pressure conserves power through anincrease in electrical resistance produced by the increased heat of thecoil when the heat sink of the surrounding liquid is withdrawn. Thisconservation of power is important in that the heater 38 is powered bybattery.

[0043] In addition, when fluid is delivered to the metal tube 40 bysqueezing the rubber bulb 36, not all the fluid is vaporized,particularly if the squeezing is strong, or rapidly repeated beforevaporization occurs. This excess fluid overflows the tube 40, runs downthe outside of the tube 40 to the bottom of an annular catch well 90between the tubes 50 and 40. This liquid, if allowed to build up, wouldrob heat from the metal tube 40. A drainage hole 60 at the bottom of thewell 90 allows the excess fluid to drain into a separate tank 62.Another drain line 63 empties condensate from the smoke chamber 14 tothe tank 62. The liquid collected in the tank 62 can then be removedthrough an access hole 64 and rubber stopper 66.

[0044]FIG. 2 shows the heat generator 30 installed in a toy gun 10, inthis case, a pistol styled like a fanciful “ray gun”. The body 16 ofthis gun includes a hollow casing of plastic or other suitable material.The gun body 16 is preferably molded from a suitable plastic in twomirror-image halves with the hand grip 20 and battery compartment 28.The smoke chamber 14 can be formed integrally therewith, but preferablyis molded separately and then secured to the front end of the gun body16 (e.g., with a snap-on action) after the two halves are mated inclam-shell fashion. Rearward depression of the trigger 22 operates toengage an axially extending actuator (or “striker”) 68 through apivoted, spring-loaded dog 70, causing a like rearward movement of theactuator from a forward position adjacent the diaphragm 74 to an extremerear position against the action of a coiled compression spring 80. Thedog 70 is mounted in a recess 68 r formed in the lower side of theactuator 68. At the rear limit position, a corner 72 of the body 16 camsthe dog 70 to pivot against its spring 71 until it releases from thetrigger 22. This release allows the actuator to slide forward propelledby the compressed spring 80 to strike an elastic diaphragm 74. It alsodefines the rear limit position of the movement of the actuator 68.

[0045] With reference to FIG. 2, the smoke chamber 14 is defined by thediaphragm 74 (forming a generally planar rear wall 14 b), a front wall14 a in generally parallel, spaced relation with the rear wall, and agenerally cylindrical side wall 14 c extending between walls 14 a and 14b. The diaphragm 74 is preferably replaceably sandwiched between thesmoke chamber 14 and the gun body 16, and it can be mounted in aseparate circular frame 76 that is so secured. A generally circularorifice 14 d is formed in the front wall as an exit port for the smokerings 12. The orifice 14 d is preferably positioned coaxially with thediaphragm 74. In the preferred form shown for a hand-held toy gun 10,the diameter of the orifice is in the range of about 1 to 3 inches, withabout 1.25 inches being generally preferred.

[0046] The upper outlet end of tube 50 of the smoke generator 30 passesthrough a lower portion of the chamber side wall 14 c to feed smokeproduced by the generator 30 to the smoke chamber. An optional light 78is attached inside the chamber wall 14 c to facilitate visual inspectionof the smoke in the chamber 14 and, in particular embodiments, to addillumination to the smoke inside the smoke chamber and/or to the ringseminating from it, particularly in darkened rooms. The chamber 40 can bemade (whole or in part) from a transparent or translucent material suchas a suitable plastic, such as polypropylene.

[0047] The ratio of the diameter of the orifice 14 d to the internaldiameter of the smoke chamber 14 is adjustable to maximize smoke ringquality and output by holding smoke in the chamber after it is produced,and then producing a well formed ring after the gun is “fired”.Typically, that ratio is as low as about 1:4, but preferably in a rangeof about 1:2 to 2:3. By way of illustration, but not of limitation, theorifice 14 d, as noted above, has a diameter of abour 1.25 inches, andthe internal diameter of the smoke chamber 40 is about 2.5 inches. Thechamber diameter ranges from 2 to 5 inches for the preferred gun 10shown in FIGS. 2 and 3.

[0048] The gun is “fired” to eject at least one smoke ring by theactuator 68 striking the diaphragm 74. The actuator in the preferredform illustrated is mounted in the body 16 at at least two axiallyseparate bearing surfaces 16 a and 16 b. The actuator 68 reciprocatesfreely along its lengthwise axis in the direction of the axial arrow 18.As shown in FIGS. 2 and 3, the actuator is approaching its forwardposition where the actuator head 82 strikes the diaphragm 74. Theresilience of the diaphragm material (and ribs 74 a) returns thediaphragm to its original shape and returns the actuator 68 to a pointwhere the trigger 22 when in its forward or unsprung position can engagethe dog 70 and the gun can be fired again. There is no limiting forwardposition to the actuator other than the diaphragm. If the actuatorstopped abruptly (or snaps) at a limit position, it is found that theensuing pressure wave is not conducive to well-formed smoke rings. Inthe preferred form, the actuator is also generally centered on thediaphragm 74 and the orifice 14 d. The coil spring 80 held in a cavity16 c formed at the center rear of the gun body urges the actuatorforward, toward the diaphragm. The spring, when compressed, provides amotive force that propels the actuator to strike the diaphragm with itshead 82 to deflect the diaphragm forwardly to thereby produce a pressurewave in the fluid in the smoke chamber 14. In the preferred form shown,the spring 80 is captured at its front end on an end boss 68 a of theactuator, and at its rear end the spring 80 abuts an adjustable stopmember 84. The stop 84 pivots freely about a pivot pin 84 a in responseto a manual movement of projecting lever 84 b. The pivot is not centeredin the main body 84 c of the stop 84 so that rotation (in the clockwisedirection as shown) produces a camming action that compresses the spring80. The force of the spring 80 on the stop, and friction with the pin 84a and the surrounding body 16, secures it against further rotation onceit is manually set. This manual rotation of the stop allows a convenientadjustment of the actuator striking force, and thereby the speed of thesmoke rings ejected by the gun 10 when it is fired.

[0049] The actuator head 82 is preferably circular with a diameter nearin size to that of the orifice 14 d. The striking face 82 a ispreferably flat. The impact of the face 82 a on the diaphragm 74deflects the diaphragm forward a short distance, one sufficient tocreate a pressure wave within the smoke chamber that in turn creates asmoke ring that ejects from the gun 10 and travels forward, in an axialdirection with respect to the gun. The quality, speed and number ofsmoke rings created depends on an interplay of factors such as thematerial, thickness, tension and mounting of the diaphragm, the rigidityof the striking face 82 a, the mass and velocity of the actuator, andthe absolute and relative sizes of the areas of the diaphragm and thestriking face that interreact. In one form, as illustrated and as notedabove, the diaphragm is an edge-mounted piece of latex rubber about 10mils thick held so that it is flat before it is struck, but notstretched to any significant degree. If the diaphragm is tensioned, theactuator impact can produce a bouncing leading to the formation ofmultiple surges per firing (which may be desirable under certaincircumstances). However, to produce a quality traveling ring with oneimpact, and use a taut diaphragm, the actuator head 82 a preferablymounts a layer of foam rubber or like energy absorbing or “lossy”material to cushion the blow.

[0050] While the preferred embodiment uses an elastic diaphragm, it willbe recognized that there are many ways to move a member to produce awavefront in an adjacent fluid. For example, a rigid or resilient membercan be mounted to move in the manner of a piston within a cylinder(e.g., the smoke chamber side wall), or the diaphragm can be coupled toa solenoid in the manner of a diaphragm in a telephone or loudspeaker,or a diaphragm can itself be formed of materials, or layers ofmaterials, that deform in response, e.g., to applied voltages in mannerthat produces the desired pressure wave. These variations are intendedto fall within the scope of the appended claims.

[0051] It is also contemplated, and it is presently preferred, to use anelastic diaphragm 74′ that is bowed or curved slightly in cross sction,e.g., ⅛ to ¼ inch measured at the center at a maximum. The direction ofthis curvature is convex with respect to the actuator head 82 (shown indashed lines in FIG. 2.). To restore this curved shape after beingimpacted by the actuator and driven toward a flat or concaveconfiguration, a set of radial ribs 74 a mutually-spaced may be formedintegrally in the diaphragm material.

[0052] Similarly, while the actuator is described as a spring-loaded,linearly reciprocating “plunger”, an equivalent striking member can beformed in a wide variety of ways well known to those skilled in the art.Some examples are pivoting strikers (using a hammer-like pivotingaction), solenoid-driven, pneumatically, and hydraulically-drivenstrikers, as well as direct drives for a rigid, piston-like diaphragm ordiaphragm mountings.

[0053] In the preferred, hand-gun form illustrated herein, the tube 40is preferably made from a metal or alloy thereof such as stainlesssteel. The envelope 42 of the heater, made from a high temperaturesilicate such as borosilicate glass, extends vertically so that itsbottom end is above the top of the liquid 24 in the tank 32, and itsupper end extends above the upper end of the metal tube 40. The metaltube 40 for a hand-gun 10 has an outer diameter of preferably 0.05 toabout 0.07 inch, more preferably about 0.0546 to about 0.066 inch.Typically, the glass tube 42 preferably has an outer diameter of betweenabout 0.049 to 0.055 inch, more preferably about 0.049 inch. A preferredradial spacing of the glass tube 42 to the inner wall of the tube 40 isbetween from about 0.001 to about 0.005 inch, preferably about 0.004inch. This spacing has been found to promote the pumped movement of asuitable volume of liquid 34 to a region adjacent the heater in responseto a pressure increase that can be produced manually, but not so muchliquid that it strongly gushes up and out of the tube 40, or requires asignificant time delay for vaporization. In the preferred form, theheater reaches its operating temperature in about 5 seconds, and smokecan then be made repeatedly, on demand, in about ½ second.

[0054] The invention is compatible with a wide range of suitable smokeprecursor liquids. However as discussed, it is an object of thisinvention to provide smoke that is essentially safe for use in settingsin which humans are present. Preferably, that smoke is made from liquidthat is approved by the U.S. Food and Drug Administration (FDA). Apreferred liquid is water having a smoke producing amount of propyleneglycol and less than about 5 ppm mineral impurities. Such liquid can beobtained from a variety of commercial sources including “Fog fluid FJ1Q,unscented” from Visual Effects Inc. of Bronx, N.Y. (USA).

[0055] The resistance coil 44 has a resistance of from between about 4ohms to about 10 ohms when cold (room temperature), and draws about 400to about 600 milliamps in normal use to produce smoke. In the absence ofliquid, the coil heat continues to draw current, but its resistanceincreases without the liquid acting as a heat sink. In this“liquid-withdrawn” state, it draws preferably about 300 to 450milliamps, a conservation of about ⅓ of the current drawn whenvaporizing (assuming a fixed voltage). The resistance coil can be madefrom a wide range of suitable materials, but nickel or alloys of nickelare preferred. Nickel that is at least about 99.9% pure is preferred foruse in the hand-gun 10 shown in FIG. 2. The preferred coil has an outerdiameter (O.D.) of about 0.02 inch.

[0056] A user of the toy gun 10 closes an electrical switch 86 to powerthe resistance coil 44 and energize the light 78. Power can be suppliedby any suitable means including the batteries 24, or a cord extension toa household electrical socket or transformer. In the preferred toy gunembodiment using batteries for maximum portability, a batterycompartment in the base 28 houses 6 AA batteries in series to provideabout 9.0 volts with fresh batteries. After use, the voltage drops toabout 7.5 volts, and after about 3 hours of use, to about 6.0 volts.

[0057] A second “trigger” 88 mounted in the hand grip 20, when depressedagainst a spring force by the user, contacts and compresses the bulb 36to increase fluid pressure in the tank 32. This spring force acting onthe trigger 88 is preferably provided by the resiliency of the bulb 36itself. This increase in fluid pressure causes a rise in level of theliquid 34 into the annular space 43 between the heater and the tube 40,toward the resistance coil 44. The small volume of liquid in this narrowannular space 43 vaporizes very quickly (about ½ second) to producesmoke. That smoke rises into and fills the smoke chamber 14. If thetrigger 88 is pulled too strongly, or too often, the pumped liquid canoverflow the tube 40. If so, it runs into the well 90 at the bottom ofthe annular space between the tubes 40 and 50 where it is drained awayso that it does not interfere with the vaporization process. Release ofthe trigger 88 lowers the fluid pressure as the resilient bulb 36expands back toward its pre-compressed configuration. This decrease fromthe increased fluid pressure level immediately causes the liquid 34 towithdraw from the space 43 adjacent the heater 38. Smoke generationthen, in most cases, ceases promptly.

[0058] The toy gun thus has a readily available supply of liquid 34 intank 32, for repeated fast production of batches of smoke “on demand”.Of course, the smoke generator 30 can be operated continuously orsemi-continously, not “on-demand”. However, continous or semi-continuousoperation requires a greater power and liquid usage, and a likely wasteof smoke that is produced, fills the chamber 14, and flows,unstructured, out of the orifice 14 d, not as rings. As discussed above,the toy gun 10 can operate generally independently of orientation sothat smoke rings can be produced with, e.g., a sideway or even upsidedown orientation, or the gun can be placed on its side when not in use.As also discussed above, the smoke generator 30 and gun 10 of thepresent invention can operate with water-based smoke precursor liquids(usually water with polyglycol, or the like, and a low level of mineralimpurities). Smoke formed from such liquids are less likely to beirritating, or to have other health hazards, than known oil-basedliquids.

[0059] Although the invention has been shown and described with respectto its preferred embodiments, it will be appreciated from the foregoingthat various other changes, omissions and additions will occur to thoseskilled in the art without departing from the spirit and scope of theinvention.

[0060] For example, while the invention has been described with respectto an air-filled, deformable bulb as a source of a variable pressureacting as the liquid 34 in the tank 32, a wide variety of otherarrangements can achieve the same end effect. The liquid can be held ina deformable tank. A piston and cylinder arrangement can vary thepressure hydraulically. A compressed air supply or gas from a CO₂cartridge can be applied to the tank. Further, while the heater has beendescribed as an electrical resistance wire in a glass envelope, a widevariety of resistance and other heaters are known that can be adapted tovaporize the liquid, whether continuously or on demand. Further, while ahand gun is described as the preferred application of the presentinvention, it will be recognized that the invention can be readilyadapted to other toys (toy rifles, bazookas, and cannons, and modeltrains and boats) and to other smoke applications (theatricalproductions). These and other modifications and variations disclosedherein are intended to fall within the scope of the appended claims.

What is claimed is:
 1. A smoke generator comprising: a) a supply tankthat holds the liquid, b) a source of variable fluid pressure in sealedfluid communication with the supply tank for increasing and decreasingfluid pressure in the tank to feed the liquid to and from a heatingunit; and c) a heater adapted to receive and vaporize a small portion ofthe liquid fed from the supply tank in response to an increase in thefluid pressure.
 2. The smoke generator of claim 1, further including: d)a first tube with a first end entering into the supply tank, and asecond smoke outlet end; and e) a heater positioned at least partiallywithin the first tube for vaporizing the pressurized liquid driven by anincrease in the pressure into a narrow annular region between theheating element and the surrounding tube.
 3. A smoke generatorcomprising: a) a tank holding a supply of a liquid that can be vaporizedto produce the smoke, b) a first tube that has a first end in fluidcommunication with the fluid in said tank and extending generallyupwardly from said tank, c) a heater disposed in said first tube abovesaid liquid in said tank, and spaced from said heater and said firsttube, and d) a variable fluid pressure source generally connected to thetank operable to force the said liquid from said tank into saidheater-to-tube space in response to an increase in the pressure producedby said variable fluid pressure source from a first level, and evacuatethe fluid from said heater-to-tube space in response to a decrease insaid pressure from said increased level, said heater vaporizing theportion of said liquid driven by said pressure increase into saidheater-to-tube space to produce the smoke.
 4. The smoke generator ofclaim 3, wherein the variable pressure source is a flexible bulb insealed fluid connection to the supply tank.
 5. The smoke generator ofclaim 3, wherein the heater comprises an electrical resistance heatersealed in a heat-conductive envelope.
 6. The smoke generator of claim 5,wherein said heat-conductive envelope is glass.
 7. The smoke generatorof claim 3, wherein said heater is generally centered in said first tubeand said heater-to-tube space is annular.
 8. The smoke generator ofclaim 7, wherein the radial dimension of said annular space is in therange of about 0.001 to about 0.005 inch.
 9. The smoke generator ofclaim 3, wherein said first tube is formed of a metal, and it forms partof an electrical connection to the electrical resistance.
 10. The smokegenerator of claim 9, wherein the metal is stainless steel.
 11. Thesmoke generator of claim 3 further comprising a second tube that isdisposed generally concentrically around said first tube and defining aliquid catch well therebetween.
 12. The smoke generator of claim 11,wherein said second tube is formed of a metal, and it forms part of anelectrical connection to the electrical resistance coil.
 13. A toysmoke-ring gun comprising: a body extending generally in an axialdirection, a smoke chamber at a front end of said body, said smokechamber having front, rear and side walls and an outlet orifice formedin a front end wall for forming smoke rings that travel axially, anaxially displaceable member forming at least part of said rear end wallthat is generally parallel to, and spaced from, said front end wall, asmoke generator whose outlet is in fluid communication with said smokechamber, and an actuator mounted on the body and operable to move thedisplaceable member to produce a wave pressure inside the smoke chamberthat causes a traveling smoke ring to be formed as a portion of thesmoke held in the smoke chamber is ejected through said orifice.
 14. Thetoy smoke-ring gun of claim 13, said smoke generator including a heater,a supply of a smoke-producing liquid in a tank, and a pressurizer actingon said liquid supply to produce on-demand smoke to said smoke chamber,and a first tube extends into said liquid supply at a lowered end andsurrounds said heater over a region above said tank.
 15. The toy gun ofclaim 14, wherein said pressurizer comprises an air-filled bulb insealed fluid communication with said smoke-generating liqud in saidtank.
 16. The toy gun of claim 15, wherein the heater is in the firsttube to vaporize the smoke, producing fluid when said pressurizer isactivated to produce an increased pressure level in such tank thatdrives said liquid upwardly into said first tube.
 17. The toy gun ofclaim 16, wherein the heating element further comprises an electricalresistance heating coil, and further comprising a battery powering saidheater coil and a switch connected therebetween to control theactivation of said coil.
 18. The toy gun of claim 17, wherein said coildraws a current of between from about 400 to 600 milliamperes with saidliquid adjacent said heater within said first tube, and draws lesscurrent, due to an increased resistance when said liquid is withdrawnfrom said first tube, in response to a decrease in the fluid pressureprovided by said pressurizer.
 19. The toy gun of claim 18, furthercomprising a sealed vessel that encloses said resistance coil and wiresextending through said vessel to connect electrically said coil to saidbattery and support it in a spaced relationship with respect to saidvessel.
 20. The toy gun of claim 19, wherein the vessel consists of aglass.
 21. The toy gun of claim 20 wherein the radial spacing betweenthe glass vessel and said first tube is between from about 0.001 toabout 0.005 inches.
 22. The toy gun of claim 21, wherein the first tubeis formed of a metal.
 23. The toy gun of claim 14, wherein the smokegenerator further comprises a second metal tube coaxial with andsurrounding said first tube and defining a catch well for said liquidtherebetween.
 24. The toy gun of claim 13 wherein said axiallydisplaceable member comprises a diaphragm of an elastic material. 25.The toy gun of claim 24 wherein said diaphragm is generally circular andedge-mounted to form at least a portion of said rear wall.
 26. The toygun of claim 25 wherein said diaphragm is formed of rubber.
 27. The toygun of claim 25 wherein said diaphragm is generally coaxial with saidorifice and said actuator is movable to strike said diaphragm to producesaid pressure wave.
 28. The toy gun of claim 27 wherein said diaphragmhas a low tension and said actuator is rigid.
 29. The toy gun of claim24 wherein said actuator is a member that is linearly slidable withinsaid body and further comprising a spring captured between a rear end ofsaid member and said body.